Drill bit center jet

ABSTRACT

A drill bit construction including a center jet for preventing the accumulation of masses of earth formation between and above the cutters, the jet being provided by a nozzle which breaks up or diffuses the stream of pressurized drilling mud issuing therefrom to avoid abrasive concentration of the jet on portions of the teeth of the cutters. In addition, a jet nozzle construction and mounting arrangement permitting installation and replacement of nozzles downwardly through the drilling mud passage in the body of the bit, there being means provided for reducing turbulence where it is not desired, while at the same time providing controlled diffusion or breaking up of the stream and also means for protecting the bit body adjacent the nozzle against undue abrasive action.

United States Patent [191 Garner 14 July 16, 1974 DRILL BIT CENTER JET3,125,115 3/1322 wedlock et al 1 ,2O7,2 l l 4 [75] Inventor: Gamer L05Alamltos 3,744,581 7/1973 M351? 175/340 [73] Assignee: SmithInternational; Inc., Newport 'y Examiner-David Brown Beach, Calif. [57]ABSTRACT [22] Flled: May 1973 A drill bit construction including acenter jet for pre- [21] Appl. No.: 361,479 venting the accumulation ofmasses of earth formation between and above the cutters, the jet beingprovided [52] U S Cl 175/340 175/422 by a nozzle which breaks up ordiffuses the stream of [51] F32") 9/08 pressurized drilling mud issuingtherefrom to avoid [58] Fie'ld 332 337 'abrasive concentration of thejet on portions of the 3 teeth of the cutters. In addition, a jet nozzleconstruction and mounting arrangement permitting installation dreplacement of nozzles downwardly through the [56] References Citeddrilling mud passage 1n the body of the bit, there being UNITED STATESPATENTS means'provided for reducing turbulence where it is 2,104,8231/1938 Sherman 175/340 n t desired, while at the same time providingcon- Goolsbee Ct fl l. trolled diffusion or breaking up of the Streamand also 5 263,??? 1313;; llzzitnerettali 1321318 I means .forProtecting the bit body adjacent the nozzl? 3:070:182 12/1962 Ru'ntef1:11:11:11:11:: 175/339 .agamstundue abras've 3,111,179 11/1963 Alberset a1. 175/340 X 1 13 Claims,9 Drawing Figures 1 DRILL BIT CENTER JETbody rotates and the cutters rotate on the body. The

pressurized stream of drilling mud mixes with the cuttings from theformation,'forming a slurry which is forced to the top of the holearound the drill string by the pressurized mud flowing down through thestring and through the ports or jets. A center jet extending downwardlythrough the dome or central underside of the tool body has been providedheretofore but it has comprised an open port or a nozzle from which asolid stream of pressurized mud issues, the stream being directed to theteeth on the rotary cutters which are closest to each other in thelongitudinal central and upper longitudinal portion of the bit unitbeneath the dome.

The highly pressurized substantially solid stream of drilling mud isquite abrasive and produces harmful wear on the cutter teeth.

It is an object of the present invention to provide a drilling toolhaving a close grouping of rotary cutters wherein there is provided acenter jet from which issues a controlled flow of pressurized drillingmud in a bro- I ken up or diffused condition, both to more effectivelyprevent the accumulation of shale balls or earth formations betweenthe-downwardly facing dome of the tool body and the relatively closelyspaced inwardly and upwardly directed portions of the rotary cutters, aswell as to prevent objectionable wear on the cutter teeth which wouldotherwise occur if the stream from the center jet was maintained in asingle highlyabrasive column or stream.

More generally, it is an object of the invention to provide a controlledjet construction in the form of a nozzle which is directed more or lesstoward the teeth of one or more cutters of a drilling tool wherein' thestream of pressurized mud is broken up or diffused to prevent wearing ofthe teeth from the abrasive action of the mud.

A further action of the invention is to provide'a drilling tool with acenter jet directed downwardly from the lower central portion of thetool at the dome thereof, wherein a nozzle is removably mounted in thejet port and is accessible for removal and replacement, as well asoriginal insertion downwardly through the conventional drilling mudpassage extending axially of the tool body and open at the top.

A further object is to provide a mounting sleeve for a jet nozzle whichis anchored in the bit boon and extends outwardly or downwardly beyondthe face of the dome of the body of the bit and secured to the dome by aweld amply filling the corner defined by the outer wall of the sleeveand the downwardly facing dome of the body in order to reduce abrasivedestruction of the metal of the bit body around the sleeve due toeddying and agitation of the drilling mud and/or cuttings.

The above and other objects and advantages of the invention will morefully appear from the following de- 2 scription in connection with theaccompanying drawtngs:

FIG. 1 is a side elevational view of a drilling bit showing it inrelationship to a drilling string to which it is attached, the drillingstring and the walls of a hole being drilled being shown in brokenlines;

FIG. 2 is an enlarged detail partially in vertical section of the lowerportion of a drill bit body with portions of rotary cutters shown inbroken lines;

FIG. 3 is a sectional view taken approximately on the line 3-3 of FIG.2; a

FIG. 4-is an enlarged detail in vertical section of a form of diffusernozzle or jet;

FIG. 5 is a sectional view taken approximately on the line 5-5 of FIG.4;

FIG. 6 is a view similar to FIG. 4 but showing a modifled form of nozzleconstruction;

FIG. 7 is a sectional view taken approximately on the line 77 ;of FIG.6; l

FIG. 8 is a view similar to FIGS. 4 and 6, showing another form ofnozzle construction;

FIG. 9 is a bottom plan view ofthe drill bit of FIG. 1.

In FIG. 1 broken lines 12 show the sides of a hole being drilled in theground. Extending into the hole are sections 14 and 16 of drill string,the section 16 comprising a sub, to the lower end of which is secured ina conventional manner, a drill bit body 18. As shown in FIG. 2 the bitbody has a lower portion 22 and downwardlyfrom the portion 22, extendlegs 24. These legs are preferably three in number and downwardly andupon which is rotatably mounted a rotary cutter 28 having teeth 30. Asshown in FIG. 9 these cutters have their teeth 30 rather closelypositioned and as viewed in FIG. 2, there is a pocket formed between theinner and upwardly disposedportions of the cutters and the underside 32of the bit body which is conventionally known as a dome.

In FIG. 2 there is shown a lubricating unit 34 of con- Mounted in thebottom portion 38, 40 of the drilling mud flow passage is a sleeve 44whose lower end 44A extends downwardly below the .face of the dome 32and the sleeve is secured to the dome by a weld 46 which preferablyfills the angle between the projecting portion 44A of the sleeve and thesurrounding adjacent face portion of the dome 32. The sleeve 44 isprovided with longitudinally intermediate internal threads 48 tothreadedly receive an inner sleeve 50. This sleeve is provided with atapered upper portion 52 which is castellated as at 54 to receive asuitable wrench or other tool for inserting and removing the innersleeve 50 relaelement 58 which extends downwardly through an opening 60in the sleeve 44. The nozzle 58 has a downwardly extending shoulder 62which bears against the upwardly facing shoulder 54 of the sleeve 44.When the nozzle 58 is clamped between the shoulder 56 and 54, the O-ring53 is placed under compression to a sufficient degree to provide a sealbetween the shoulder 54, the bottom end of sleeve 50 and the adjacentcircumferential portion of the nozzle 58.

The upper inner end portion of the sleeve 44 is tapered as at 64. Thetaper 64 of the sleeve 44 is provided to permit relatively smooth flowof pressurized drilling mud downwardly through the passage 37, itsreduced diameter 38 and into the sleeve and nozzle structure justdescribed.

The nozzle 58 may be provided with an enlarged inlet portion 66. This isto provide a relatively smooth inlet flow into the upper end of thenozzle. From the upper portion the nozzle may be cylindrical asindicated'at 68. The lower end of the nozzle 58 is provided withvertical slots 70 and these slots lie between legs 72 which are shown tobe three in number in the specific embodiment. The ends of the legs 72are turned downwardly and inwardly toward each other to provide adownwardly disposed central outlet portion 74 and outlets through thespaces 70 between the legs 72. Thus the stream of pressurized drillingmud issuing from the nozzle 58 is not confined to a single more or lesssolid stream but is broken up by the inwardly turned ends of the legs 72and diffused flow of drilling mud is permitted downwardly through thebottom opening 74 and laterally outwardly through the openings 70between the legs 72. This diffusion of the flow renders the drilling mudhighly efficient at this point in preventing the accumulation of shalecuttings into hard lumps or balls and also eliminates the destructiveabrasive action which is found when a single high pressure stream ofdrilling mud is directed downwardly against the more inwardly disposedteeth 30 of the rotary cutters 28. The arrows 76 indicate generally themanner in which the drilling mud is diffused as it flows from thenozzle. The nozzle of FIG. 2 and FIG. 4 is also illustrated in .FIG. 3.The latter figure shows the central position of the nozzle relative tothe drill bit body 22. FIG. 3 illustrates the manner in which some drillbit bodies are formed in three sections 22A, 22B and 22C. These sectionsare shown with abutting portions connected by a weld 78. This weldsurrounds the central jet area, as shown in FIG. 3, and may also lieabout a circumferential jet 81 of a more conventional type and location.In forming the ports in which the nozzles are mounted, the threepiecedrill bit body is welded together by the welds 78 and then the ports arebored in their proper locations, the sleeves 44 are welded in place andthe jet nozzles areinstalled downwardly through the pressurized mudpassage 37. I

FIGS. 6 and 7 show a nozzle 80 having three downwardly extending legs82, the lower ends of which have rounded inwardly directed portions 84which create a turbulence in the same manner as the inwardly turned endsof the legs 72 shown in FIG. 4. In FIG. 8 there is shown a modificationwherein there is a sleeve 86 secured in the drill bit body 22 by a weldas shown. The sleeve 86 is provided with a downwardly facing shoulder 88to engage a complementary shoulder formed in the body 22. The inside ofthe sleeve 86 has athreaded portion 92 which is engaged by threads on aninner sleeve with a downwardly facing shoulder 94. Located in the innersleeve 90 is a nozzle 96 having anupwardly disposed shoulder 98 engagingthe downwardly directed shoulder 94 of the inner sleeve 90.

The nozzle 96 rests upon an upwardly disposed shoulder 100 in the outersleeve 86 and is clamped between it and the shoulder 94 of theinner'sleeve 90. Between the lower end of the inner sleeve 90 and theshoulder 100 is an O-ring 102 which forms a seal between the outer andinner sleeves and the nozzle.

It should be noted that the inner bore 104 of the nozzle 96 iscylindrical in shape. Ordinarily this would provide a rather smooth flowthrough the nozzle but in this instance, it is provided with an innerwall which is rough in texture. This causes the mud stream which comesin contact with the wall of the nozzle to be slowed, slowing the entirestream to some extent but at the same time, producing a turbulence ofthe stream in the nozzle so that it will not flow out in a solid more orless cylindrical stream. In other words, it will tend to break up andnot concentrate itself in a single stream on any part of the rotarycutter or cutters.

l have shown seal means in the form of O-rings in the nozzle assemblyitself. It is highly desirable that there be a seal between the outersleeve and the wall of the port formed through the drill bit body 22. Ifthere is any leakage between the outside of the outer sleeve and thewall of the bore of the body in the drill bit there will eventually besufficient abrasive action to erode the bit body and the .outer portionof the sleeve and destroy or displace the nozzle assembly. The weldbetween the downwardly projectinglower end of the outer sleeve below thesurface of the dome 32 not only securesthis sleeve in the bit body butalsoprovides a complete seal between the bit body and the sleeve whichis anchored therein. Thus, there is no possibility of leakage anderosion between the bit body and said sleeve.

From the foregoing it will be seen that l have provided a drill bitconstruction particularly adapted for use with rotarycutters whereinmeans is provided for breaking up the stream issuing from a drilling mudnozzle so that it will not erode away or wear the teeth on the cutter.Furthermore, where a grouping of cutters is utilized as in conventionaltypes of rotary cone drilling bits, a central controlled jet through oneof the nozzles will prevent the formation of earth formation or shalepacking below the dome of the bit body and between the cutters, whichconventionally arethree in number where rotary cones are used. Not onlydoes the stream from the center jet or nozzle prevent the formation ofshale ballsand earth formation but in so doing, the stream of drillingmud is broken up or diffused so that there is not any concentratedabrasive action on any portion or portions of the rotary cutters. WhileI have illustrated several types of jet nozzles for creating diffusionof the stream, it is of course understood that many various types andshapes of nozzles can be devised and utilized with the result ofbreaking up or diffusing the mud stream for the purposes abovedescribed.

The construction and arrangement of the nozzles and their anchoringsleeves provide for original insertion of the anchored outer sleeve, theremovable inner sleeve and nozzle downwardly through the usual drillingmud passage which extends axially through the bit body and is open atthe top. In addition to the original installation my arrangement permitsthe removal and replacement of nozzles without requiring major repairsto the tool.

It should of course be understood that various changes can be made inthe form, details, arrangement and proportions of the various partswithout departing from the spirit of the invention.

1 claim:

l.'A center jet drill bit construction including a rotary bit bodyhaving cutter journals downwardly and inwardly directed from spacedouter portions of the body and having closely positioned rotary cuttersthereon, the body having a downwardly directed dome face between andinwardly from the journals, the dome face and inwardly and upwardlydisposed cutter sectors defining a pocket in which shale formationparticles collect and adhere to each other in massed ball-likeobstructions to drilling mud circulation, the drill body having anupwardly open internal longitudinal drilling mud passage including a mudoutlet port directed downwardly through the dome surface, said portcomprising a diffusion element to direct a diffused stream ofpressurized drilling mud into said pocket and prevent the formation ofshale balls, said diffusion element comprising mud flow control'meansfor preventing the stream of drilling mud from impinging in aninjuriously high pressure abrasive stream concentration on the inwardlyand upwardly disposed sectors of the rotary cutters.

2. The structure in claim 1, and the mud flow control means comprising anozzle portion having an internal flow passage,- the flow surface ofwhich has a different coefficient of friction than that of the drillingmud passage in the bit body. I

3. The structure in claim 1, and the mud flow control means comprising amud stream agitator nozzle in the outlet port.

4. The structure in claim 3, and said agitator nozzle having a mud flowpassage defined by wall portions tapering in shape from cylinders ofrevolution about the longitudinal axis of the mud flow passage.

5. The structure in claim 1, and there being a plurality of saidjournals and cutters located about the rotational axis of the bit body,and said mud flow control means having means for breaking up thedrilling mud stream and directing its flow downwardly and outwardlymultidirectionally from the mud outlet port.

6. The structure in claim 5, and the mud flow control means comprising aventuri throat.

7. The structure in claim 2, and the mud flow control means comprising anozzle unit having a portion extending below the dome face, theextending portion having downwardly and laterally directed outlets andhaving mud stream interceptors adjacent the outlets to break up theunidirectional characteristics of the mud stream, a plurality of saidjournals and cutters being lo-.

characteristics of the mud stream.

8. The structure in claim 7, and the mud flow control means comprising anozzle portion having an internal flow passage, the flow surface ofwhich has a different coefficient of friction than that of the drillingmud passage in the bit body, the flow surface of the nozzle flow passagebeing roughened to dampen the pressure flow of drilling mudtherethrough.

9. A center jet drill bit construction including a rotary bit bodyhaving cutter journals downwardly and inwardly directed from spacedouter portions of the body and: having closely positioned rotary cuttersthereon, the body having a downwardly directed dome face between andinwardly from the journals, the dome face and inwardly and upwardlydisposed sectors defining a pocket in which shale formation particlescollect and adhere to each other in massed ball-like obstructions todrilling mud circulation, the drill body having an upwardly openinternal longitudinal drilling mud passage including a mud outlet portdirected downwardly through the dome surface to direct a stream ofpressurized drilling mud into said pocket and prevent formation of'shaleballs, said port having a fixed sleeve therein extending outwardlythrough the port beyond 'the dome face of the bit body, the outwardlyextending outer wall portion of said sleeve defining a bight withthe'adjacent portion of the dome face, a metal weld in said bight toanchor the sleeve and provide a fluid tight seal between the sleeve andthe outer end of the port, the sleeve having an upper end portioncomprising an upwardly open nozzle receiver of a width less than that ofsaid upwardly open longitudinal drilling mud passage, a mud flowcontrolling unit of a sizecapable of being insertible downwardly throughsaid drilling mud passage and positioned in and closely fitting thenozzle receiver of said sleeve, and the nozzle unit including meansaccessible through said drilling mud passage and securing the nozzle inthe sleeve. I

10. The structure in claim 9, and said nozzle unit securing meanscomprising an upwardly removable sleeve of less width than that of saiddrilling mud passage and threaded into the upper end of the fixed sleeveand engaging and securing the nozzle unit in the fixed sleeve.

11. The structure in claim 10, and said nozzle unit having an upperportion spaced from the adjacent upper and inner wall of thefixedsleeve, and said retaining means being threaded into the upper endof the fixed sleeve between the latter and the spaced upper portion ofthe nozzle unit. v

12. The structure in claim hand the upper inner wall of the fixed sleevebeing threaded, the upwardly removable retaining sleeve having externalthreads and an internal downwardly facing abutment, the fixed sleevehaving, below its threaded portion, and internal upwardly facingabutment, the removable sleeve being threaded into the fixed sleeve, andthe nozzle unit being secured in the fixed sleeve between the twoabutments.

13. The structure in claim 12, and a seal in the fixed sleeve betweenthe upwardly facing fixed sleeve abutment and the lower end of theremovable retaining sleeve and also about the lower end of the nozzleunit.

1. A center jet drill bit construction including a rotary bit bodyhaving cutter journals downwardly and inwardly directed from spacedouter portions of the body and having closely positioned rotary cuttersthereon, the body having a downwardly directed dome face between andinwardly from the journals, the dome face and inwardly and upwardlydisposed cutter sectors defining a pocket in which shale formationparticles collect and adhere to each other in massed ball-likeobstructions to drilliNg mud circulation, the drill body having anupwardly open internal longitudinal drilling mud passage including a mudoutlet port directed downwardly through the dome surface, said portcomprising a diffusion element to direct a diffused stream ofpressurized drilling mud into said pocket and prevent the formation ofshale balls, said diffusion element comprising mud flow control meansfor preventing the stream of drilling mud from impinging in aninjuriously high pressure abrasive stream concentration on the inwardlyand upwardly disposed sectors of the rotary cutters.
 2. The structure inclaim 1, and the mud flow control means comprising a nozzle portionhaving an internal flow passage, the flow surface of which has adifferent coefficient of friction than that of the drilling mud passagein the bit body.
 3. The structure in claim 1, and the mud flow controlmeans comprising a mud stream agitator nozzle in the outlet port.
 4. Thestructure in claim 3, and said agitator nozzle having a mud flow passagedefined by wall portions tapering in shape from cylinders of revolutionabout the longitudinal axis of the mud flow passage.
 5. The structure inclaim 1, and there being a plurality of said journals and cutterslocated about the rotational axis of the bit body, and said mud flowcontrol means having means for breaking up the drilling mud stream anddirecting its flow downwardly and outwardly multidirectionally from themud outlet port.
 6. The structure in claim 5, and the mud flow controlmeans comprising a venturi throat.
 7. The structure in claim 2, and themud flow control means comprising a nozzle unit having a portionextending below the dome face, the extending portion having downwardlyand laterally directed outlets and having mud stream interceptorsadjacent the outlets to break up the unidirectional characteristics ofthe mud stream, a plurality of said journals and cutters being locatedabout the rotational axis of the bit body, said mud flow control meanshaving means for breaking up the drilling mud stream and directing itsflow downwardly and outwardly multidirectionally from the mud outletport, and the mud flow control means comprising a nozzle unit having aportion extending below the dome face, the extending portion havingdownwardly and laterally directed outlets and having mud streaminterceptors adjacent the outlets to break up the unidirectionalcharacteristics of the mud stream.
 8. The structure in claim 7, and themud flow control means comprising a nozzle portion having an internalflow passage, the flow surface of which has a different coefficient offriction than that of the drilling mud passage in the bit body, the flowsurface of the nozzle flow passage being roughened to dampen thepressure flow of drilling mud therethrough.
 9. A center jet drill bitconstruction including a rotary bit body having cutter journalsdownwardly and inwardly directed from spaced outer portions of the bodyand having closely positioned rotary cutters thereon, the body having adownwardly directed dome face between and inwardly from the journals,the dome face and inwardly and upwardly disposed sectors defining apocket in which shale formation particles collect and adhere to eachother in massed ball-like obstructions to drilling mud circulation, thedrill body having an upwardly open internal longitudinal drilling mudpassage including a mud outlet port directed downwardly through the domesurface to direct a stream of pressurized drilling mud into said pocketand prevent formation of shale balls, said port having a fixed sleevetherein extending outwardly through the port beyond the dome face of thebit body, the outwardly extending outer wall portion of said sleevedefining a bight with the adjacent portion of the dome face, a metalweld in said bight to anchor the sleeve and provide a fluid tight sealbetween the sleeve and the outer end of the port, the sleeve having anupper end portion comprising an upwardly open nozzle receiver of a widthless tHan that of said upwardly open longitudinal drilling mud passage,a mud flow controlling unit of a size capable of being insertibledownwardly through said drilling mud passage and positioned in andclosely fitting the nozzle receiver of said sleeve, and the nozzle unitincluding means accessible through said drilling mud passage andsecuring the nozzle in the sleeve.
 10. The structure in claim 9, andsaid nozzle unit securing means comprising an upwardly removable sleeveof less width than that of said drilling mud passage and threaded intothe upper end of the fixed sleeve and engaging and securing the nozzleunit in the fixed sleeve.
 11. The structure in claim 10, and said nozzleunit having an upper portion spaced from the adjacent upper and innerwall of the fixed sleeve, and said retaining means being threaded intothe upper end of the fixed sleeve between the latter and the spacedupper portion of the nozzle unit.
 12. The structure in claim 10, and theupper inner wall of the fixed sleeve being threaded, the upwardlyremovable retaining sleeve having external threads and an internaldownwardly facing abutment, the fixed sleeve having, below its threadedportion, and internal upwardly facing abutment, the removable sleevebeing threaded into the fixed sleeve, and the nozzle unit being securedin the fixed sleeve between the two abutments.
 13. The structure inclaim 12, and a seal in the fixed sleeve between the upwardly facingfixed sleeve abutment and the lower end of the removable retainingsleeve and also about the lower end of the nozzle unit.